Many devices are now provided with near-field communication functions. The most widespread are mobile telecommunication devices (e.g., mobile phones or smartphones) which are increasingly often provided with a near-field communication interface, generally referred to as an NFC router, conferring additional functionalities on the phone. NFC routers enable a mobile device to operate either in card mode, the device then having the functions of a contactless communication card, or in reader mode, the device then having the functions of a contactless card reading and/or writing terminal.
Whether in card mode or in reader mode, the NFC router is powered by the battery of the device that contains the router. The battery of the device itself is generally charged by being connected, via a charger, to, e.g., the electrical distribution network, dynamo, solar panel, etc.